Modelling Standards

The layout will be constructed in HO Scale (1:87). Phase I will be a shelf layout, with a nominal shelf width of 12", increased as necessary in room corners. Shelves will be supported from the walls, with no legs required. Construction will be physically modular, with minimal electrical and mechanical connections between segments, and with each segment no longer than 8' in length. Shelf fascia will extend at least 6" down from the front edge of the shelf, be painted green (CPR) or brown (LCM) in control areas, white in interlocking towers, and black otherwise, and all operational controls and indicators will be located on the fascia board. Track layouts, in white (on green or black background) or black (on brown or white background), will be provided to visually indicate the function of all operational controls.

Track Standards

All tangent track clearances will be a minimum of AAR Plate 'B', with nominal clearances meeting both AAR Plate 'F' and NMRA Standard S-7 requirements. Minimum turnout geometry is No. 4, with No. 6 required where operating speeds are greater than 5 m.p.h, and curve radii range from 20" to 40" , for operating speeds ranging from 5 to 45 m.p.h. Six-axle units and locomotives with greater than 24' rigid wheelbase are prohibited from track built to less than 32" radius and from operating over No. 4 turnouts.

Wiring Standards

Layout buss wiring will provide the following main circuits:

• DCC track circuit, driven by 5A booster
• DCC accessory circuit, driven by 5A booster
• conventional DC track circuit
• conventional DC throttle feed
• emergency safety cutout loop

A single DC throttle can be connected at any point on the throttle feed buss, using a 1/4" phone plug.

Both the DC feed and the DCC booster output are routed through the master track relay so that the track circuit kill loop can de-energize all track power on both busses. The DCC accessory booster output is not routed through the master relay; DCC accessories can still be operated when the main track circuit is de-energized to allow for turnout and routing changes.

All wiring will meet NMRA Standard S-9, Standard S-9.1, and the Canadian Electrical Code provisions.

Control Systems

All mainline operational features, including signal systems and turnouts, will be operated either by DCC decoders or modular networked digital control systems. This will minimize the amount of control wiring required, as individual control runs need only run from the device to the nearest decoder, and wiring around the layout need only be the busses described above. This will also facilitate computer control of major systems.

Local yard turnout control will generally be effected by local switches, either as route selectors or individual operating handles. Mainline yard turnouts must still be operable digitally.

A track circuit kill facility will be provided, with clearly-labelled red octagonal STOP buttons no further than 8' apart around the layout fascia. These buttons will be linked into the emergency safety cutout loop, along with other protection devices such as end-of-track sensors and bridge-out interlocks. Activation of any device in the loop will drop out relays feeding both the DCC track circuit and conventional DC track circuit.

All safety interlocks and warning circuits will

• be designed using positive control and designed where possible to resort to the safest mode of operation in the event of power failure, disconnection of a circuit connector, failure of any switch to operate, or break or disconnection of any circuit cable
• where provided with a manual means of overriding the interlock or cancelling the warning, such override must be provided by either a momentary switch or a time-limited switch, and such switch must be located within clear visual sight of the equipment or facility which the circuit is intended to protect

Uniformity of Controls

Operating controls, switches and indicators will conform to the following standard:

Buttons and switches:

• Green handle: main track block selector/isolator
• Yellow handle: yard or siding block selector/isolator
• White handle: yard sub-block isolator
• Red handle: yard turnout local switch
• Silver handle: local bungalow test switch
• Red rotary: yard route selector
• Large round black button: main track junction/wye/siding turnout toggle
• Large round red button: main track yard turnout toggle
• Small round black/red button pair: secondary track turnout normal/reverse (local control)
• Small round black button: safety circuit local over-ride
• Large red (square/octagonal) button: emergency cut

Indicators:

• RG LED: turnout normal (green) or reversed (red)
• RGY LED: block power DC (green/red) or DCC (yellow)
• G/altRY LED: safety warning
• White LED: concealed presence detector
• Yellow LED: concealed limit detector
• Red LED: concealed limit detector near trip point

Interlocking tower indicators (on modelboard):

• White LED: circuit occupancy
• Red LED: OS circuit occupancy
• Yellow LED: power or protective circuit status

Interlocking tower indicators (on switchboard):

• Yellow LED: switch reversed
• Red LED: signal blocked
• Green LED: signal cleared, or switch normal
• RGY LED: block power DC (green/red) or DCC (yellow)
• Orange LED: data circuit active (code line send/receive)

Jacks:

• Red ring: DC throttle input
• Black or no ring: Digital tethered throttle input